In the art of producing hydrocarbons from underground production zones, it is usually necessary to form a wellbore down through the oil bearing strata, cement a casing into the wellbore; and, thereafter communicate the hydrocarbon containing formation with the surface of the earth. This is generally accomplished in all sorts of different specific manners by perforating the casing and thereafter flowing the hydrocarbons up a tubing string. It is advantageous to isolate the lower production zone by the employment of a packer device interposed between the casing and the tubing string, so that flow from the formation can be confined to the upper tubing string.
In U.S. Pat. No. 3,706,344 to Roy R. Vann, there is taught a permanent completion method and apparatus by which the above can be accomplished in an improved manner so that more economical production can be obtained. In U.S. Pat. Nos. 3,871,448; 3,931,855; and 4,040,485 to Roy R Vann, et al there is disclosed a packer actuated vent assembly by which the before mentioned well completion techniques can be accomplished. These techniques work satisfactory when carried out in vertical boreholes, but when the borehole is slanted, sometimes difficulty is encountered, especially when the slanted part of the borehole approaches the horizontal, as seen in the Vann U.S. Pat. No. 4,194,577; for example.
There are many instances where the lower marginal end of a borehole approaches a horizontal plane. For example, when drilling multiple boreholes from a single platform, it is not unusual to form a multiplicity of slanted boreholes which radiate from a single platform.
The present invention provides a vent assembly which enables the method set forth in U.S. Pat. No. 3,706,344 to be carried out in slanted boreholes in a more satisfactory manner.